Since the last reporting period, a total of 5 patients have been studied under this protocol. These patients have received both I- 131 labeled B72.3, approximately 10 mCi and 1 mg, and I-125 labeled BL-3 (non-specific monoclonal antibody, approximately 2 mCi and 1 mg). The antibodies were co-infused to determine the specificity of localization at time of the patient's surgery. Counting of resected samples demonstrated tumor specific uptake. Both the ratios of tumor to non-tumor and specific to non-specific antibody demonstrated the specificity of localization. No toxicity was observed. The further plans are to utilize In-III B72.3 IgG because of the improved characteristics of this isotope. The preliminary studies have been performed and showed stability and retention of immunoreactivity of the indium labeled conjugate. In addition, studies with F(ab')2 fragments will be performed.